Man-size manholes of older construction, which are made of brick, concrete or concrete formed pieces, show signs of corrosion or wear after a certain time due to environmental influences. In particular, access shafts for wastewater networks, on the bases of which channels are formed, which form connections between wastewater pipes running into the manholes, are additionally subjected to severe loads by wastewater which can contain aggressive substances.
The surface of the material from which the manhole is built is attacked by corrosion. Different restoration methods are used in order to repair these manholes which are stressed by corrosion. In addition to coating the existing building fabric with different materials, restoration by inserting prefabricated components in manhole bases and in rising manhole components, i.e. in components forming wall areas, are state of the art.
In order to be able to carry out renovation work on site on the manhole base as effectively as possible, a prefabricated manhole base liner made of plastic, adapted to the manhole base to be renovated, is introduced into the manhole, arranged at the base of the manhole, if necessary, connected with pipes opening into the manhole and backfilled with concrete. If necessary, the inner surface of the wall of the manhole is also lined with a prefabricated manhole wall liner, which may also be fixed to the wall and, for example, be filled with concrete.
Since the entrance to the manhole has a considerably smaller clear width in the case of many wastewater manholes than the base of the manhole on which the manhole base liner made of plastic is arranged, either first the upper part of the manhole has to be removed or replaced when using prefabricated renovation components with currently existing renovation methods, or the manhole base liner made of plastic is divided into sections, which are joined together again in the manhole. Since both methods are very time-consuming and labor-intensive, this also has a negative effect on the costs and duration of the renovation. In addition, removal of the upper manhole components (cone) is not always possible.
A manhole base liner which consists of folding parts connected to one another by means of hinges, is known from DE 101 29 860 A1. However, these hinges are, on the one hand, difficult to manufacture and, on the other hand, form weak points, both as regards the mechanical strength as well as the tightness of the manhole base liner, and require reworking of the seams.
In the case of known production methods for manhole base liners made of plastic for renovation, a negative form made of plastic is produced on the basis of the manhole geometry of the manhole to be renovated, to which the material from which the manhole base liner is produced is then molded.
In known methods for the production of concrete manhole base sections for the new construction of manholes, negative forms of foamed plastic are milled or cut out according to the required manhole geometry, which are used for shaping the channel geometry in the concreting process. Since the surface of such a negative form of foamed plastic is very porous and rough, the surface must be sealed or coated before applying the material from which the manhole base liner is formed. This ensures that the negative form can be removed from the finished manhole lower part without destruction and that the manhole lower part has a surface that is as smooth as possible. A disadvantage of this is that the sealing or coating of the negative form entails a not inconsiderable expenditure of time and costs.
The invention is therefore based on the object of providing a manhole base liner, a method for producing a formed part, in particular a manhole base liner for a wastewater manhole, and a method for lining a manhole, in particular a wastewater manhole, of the type mentioned at the outset of the prior art which does not have the disadvantages of the prior art. On the one hand, the production process for a manhole base liner or for a formed part, for example, a concrete manhole base section, is to be simplified and, on the other hand, the work required in a manhole restoration is to be reduced.